Question

Among the elements Li, K, Ca, S and Kr which one has the lowest
first ionization enthalpy? Which has the highest first ionization
enthalpy?

Answer 1

in a group going down ionization enthalpy decreases & in period from left to right ionization enthalpy increases
hence highest ionization enthalpy is Kr and lowest is K 

Answer 2

Answer:K has the lowest ionization enthalpy

kr has highest ionization enthalpy

Explanation:

it is because from left to right i.e, ionization enthalpy increases and from top to bottom it decreases. That is the reason why K has lowest ionization enthalpy and Kr has highest ionization enthalpy.

hope you can understand!!!!